photos of sakurajima, the most active volcano in japan, by (click pic) takehito miyatake (previously featured) and martin rietze. volcanic storms can rival the intensity of massive supercell thunderstorms, but the source of the charge responsible for this phenomenon remains hotly debated.
in the kind of storm clouds that generate conventional lightning, ice particles and soft hail collide, building up positive and negative charges, respectively. they separate into layers, and the charge builds up until the electric field is high enough to trigger lightning.
but the specific mechanism by which particles of differing charges are separated in the ash cloud is still unknown. lightning has been observed between the eruption plume and the volcano right at the start of an eruption, suggesting that there are processes that occur inside the volcano to lead to charge separation.
volcanic lightning could yield clues about the earth’s geological past, and could answer questions about the beginning of life on our planet. volcanic lightning could have been the essential spark that converted water, hydrogen, ammonia, and methane molecules present on a primeval earth into amino acids, the building blocks of life.
Slot canyons are formed when water from seasonal flash floods rush through cracks in the ground. Formed mostly in sandstone or limestone rock, these canyons are normally much deeper than they are wide. Over periods of tens of thousands of years, the turbulent rushing water erodes the rock, smooths the walls and forms the amazing natural landforms that we see today. The erosive quality of the water is further enhanced by the tiny particles of sand that are carried with it.
The greatest concentration of slot canyons anywhere in the world can be found in the state of Utah, in the U.S. People hiking down into these beautiful, winding maze of canyons need to be constantly aware that these are, very simply, just dry stream beds that provide natural waterways when the rainy season returns. Rainstorms, both local and distant, can cause dangerous flash flooding. Canyon guides advise hikers to avoid venturing into them if there is any sign of rain in the forecast. Many slot canyons will flood quickly and it may be miles before a safe exit or rescue is possible.